A middle-aged woman presented in November 2023 with exertional dyspnea and a chronic cough for three months. She had undergone a repeat mitral valve replacement (MVR) surgery five months prior. She had a tissue MVR in 2016, which degenerated, making her symptomatic, and hence had to be replaced with a metallic valve. As the respiratory symptoms recurred two months post-op, she was evaluated for the integrity of the newly placed mitral valve, which was found to be functioning well. The left ventricular function was well preserved, and she had no vegetation or clots. She was therefore investigated further for other possible causes. Chest X-ray showed a strange saucer-shaped (or disc-shaped) opacity above the middle portion of the right hemidiaphragm, which itself was found to be elevated. An ultrasound of the chest ruled out subpulmonic pleural effusion and confirmed right hemidiaphragm palsy. A computed tomography (CT) scan of the thorax was suggestive of a strange-shaped collapse of the right lower lobe with tortuous air bronchograms and a small intraluminal soft tissue shadow in the right lower lobe bronchus. A bronchoscopy confirmed collapsing segments of the right lower lobe due to external compression. It also ruled out any intrabronchial pathology causing obstruction, effectively confirming that the tissue shadow was probably just a mucus plug. A possible phrenic nerve injury during thoracotomy at the time of MVR was thus concluded. A diaphragmatic plication was advised considering that she had significant orthopnea and low peripheral oxygen saturation and that the collapsed lung would not possibly expand beyond six months or so and could in itself act as a focus for further mucus stagnation, leading to infection and further bronchiectasis, which had probably already started developing. It was difficult to persuade the patient for a third thoracotomy and she took much time to decide. Good counselling, rapport building, and assurance that, although the lung may not fully expand beyond six months, at least the orthopnea would significantly improve, she finally consented to diaphragmatic plication, which was done after 10 months of the MVR surgery. Aggressive post-operative chest physiotherapy and rehabilitation were promptly initiated. The lung completely expanded one month post-op and was thus successfully salvaged.